3–14
Hardware Interface
29 September 1997 – Subject To Change
21164PC Signal Names and Functions
Table 3–2 lists signals by function and provides an abbreviated description.
Table 3–2 21164PC Signal Descriptions by Function
(Sheet 1 of 3)
Signal
Type Count Description
Clocks
clk_mode_h<1:0>
I
2
Clock test mode.
cpu_clk_out_h
O
1
CPU clock output.
osc_clk_in_h,l
I
2
Oscillator clock inputs.
st_clk1_h
O
1
Bcache STRAM clock output.
st_clk2_h
O
1
Bcache STRAM clock output.
st_clk3_h
O
1
Bcache STRAM clock output.
sys_clk_out1_h
O
1
System clock output.
sys_clk_out2_h
O
1
System clock output.
sys_reset_l
I
1
System reset.
Bcache
data_h<127:0>
B
128
Data bus.
data_adsc_l
O
1
Data RAM address load enable.
data_adv_l
O
1
Data RAM address advance enable.
data_ram_oe_l
O
1
Data RAM output enable.
data_ram_we_l<3:0>
O
4
Data RAM write-enable bits.
index_h<21:4>
O
18
Index.
lw_parity_h<3:0>
B
4
Data check.
tag_data_h<32:19>
B
14
Bcache tag data bits.
tag_data_par_h
B
1
Tag data parity bit.
tag_dirty_h
B
1
Tag dirty state bit.
tag_ram_oe_l
O
1
Tag RAM output enable.
tag_ram_we_l
O
1
Tag RAM write-enable.
tag_valid_h
B
1
Tag valid bit.